As the Northern American Global Positioning System (GPS) gains its popularity, the European Galileo positioning system and the Russian Global Navigation System (GLONASS) are gradually established, and the China Compass Navigation Satellite System (CNSS) is anticipated to be completed in 2020, applications of Global Navigation Satellite Systems (GNSS) shall become more prevailing. Therefore, a GNSS receiver, rather than being limited to a conventional GPS receiver, would be an all-in-one GNSS receiver integrating the GPS, the GLONASS and the Galileo positioning systems. The all-in-one GNSS receiver is capable of receiving different GNSS signals for positioning or simultaneously receiving more than two GNSS signals to position more accurately, so as to provide reliable navigation information.
The GNSS receiver may simultaneously support various positioning systems; however, with respect to the hardware, a large number of signal paths are needed to process signals of different frequency bands. For example, in U.S. Pat. No. 7,358,896, a multi-band GNSS receiver capable of supporting the GPS, the Galileo and the GLONSS positioning systems is provided. The multi-band GNSS receiver has three signal paths for respectively processing signals of three different frequency bands, and accordingly circuit cost is increased. According to the present invention, various GNSS signals are received by integrating radio frequency (RF) receiving circuits to reduce the circuit cost.